1. Field of the Invention
This invention relates to a process for recovering the transition metal component of catalysts used in the hydroconversion of hydrocarbonaceous materials.
2. Background of the Invention
Various hydroconversion processes exist for catalytically converting heavy hydrocarbonaceous material to lower molecular weight more valuable products. Many of these processes use catalysts which contain transition metals, such as molybdenum. Processes which employ transition metal catalysts, typically molybdenum catalysts, include the hydroconversion of residual oils, as well as the liquefaction of solid hydrocarbonaceous materials, such as coals, tar sands, and the like. During the processing of these materials, the molybdenum typically becomes dispersed in the form of molybdenum sulfide, either on the material in a slurry of product liquids, or added oil. As the process progresses, most of the molybdenum (from both the catalyst and from the material being converted) becomes concentrated in the solid residue. Therefore, the recovery of molybdenum, used for catalytic hydroconversion of heavy hydrocarbonaceous materials should be based on the recovery of molybdenum from these solid residues. One problem associated with recovering molybdenum from the solid residue material is that the content of molybdenum in the residue, based on the total weight of the residue, is relatively small. On the other hand, solid residues contain significant amounts of organic substances and their heat of combustion is close to the heat of combustion of solid hydrocarbonaceous materials such a coal, which is used for heating and electricity production. Thus, it would be wasteful to use such solid residues only as the raw material for molybdenum recovery.
Consequently, there is a need in the art for a process which can efficiently recover molybdenum by first realizing substantially the full employment of the fuel potential of the solid residue, followed by extraction of molybdenum from the combustion products where the concentration of molybdenum is significantly higher than in the source solid residues.